ML103570387

Requests for Clarification (Snpb) EPU LAR Review

ML103570387
Person / Time
Site:	Point Beach
Issue date:	12/21/2010
From:	Beltz T Plant Licensing Branch III
To:	Hale S Nextera Energy
beltz T, NRR/DORL/LPL3-1, 301-415-3049
References
TAC ME1044, TAC ME1045
Download: ML103570387 (2)

Text

From:

Beltz, Terry Sent:

Tuesday, December 21, 2010 11:53 AM To:

Hale, Steve Cc:

Abbott, Liz; Costedio, James; Flentje, Fritzie; Hanneman, Harv

Subject:

Point Beach Nuclear Plant, Units 1 and 2 - Request for Additional Clarification (SNPB) re: Extended Power Uprate Review (TAC Nos. ME1044 and ME1045)

Dear Mr. Hale:

The NRC staff in the Nuclear Performance and Code Review Branch (SNPB) in the Office of Nuclear Reactor Regulation requires some additional clarification related to the following:

Follow-up to RAI 2.8.5.6-8 from the May 20, 2010, response letter (ADAMS Accession No. ML101440069):

SNPB-1 Although LHSI is not interrupted during the switchover from injection to the recirculation mode, HHSI is terminated. For a small break in the range of 2 - 6 inches in diameter, RCS pressure can remain above the shutoff head of the LHSI pump (134 psia) for a couple of hours. As such, there will be a period during the LOCA when there is no injection until the HHSI pumps are re-aligned. For small breaks on the top or side of the cold discharge leg, RCS pressure can limit the fluid in the core and upper plenum to reduced values compared to breaks on the bottom of the pipe. Therefore, when HHSI is terminated with RCS pressure above 134 psia, core uncover can occur if HHSI is not initiated within 15 minutes of drainage of the RWST.

How are small cold leg breaks in the 2 - 6 inch range handled when RCS pressure remains above the shutoff head of the LHSI pump and HHSI is terminated when the RWST drains?

How do the EOPs deal with this particular scenario? That is, if a SBLOCA occurs and RCS pressure remains above 134 psia, then the operators will need to immediately re-align HHSI to the sump to assure the time during the LOCA without any injection is minimized to limit the PCT. Please explain how this condition is handled.

SNPB-2 Background and additional clarification requested regarding the potential for injection for extended periods of time following SBLOCAs and a possible inadvertent rapid depression:

As a result of staff calculations for small breaks, failure of an ADV to open and the possible need for the PORVs to be opened to ensure a timely cooldown to actuate LPSI could be required. The staff RELAP5 calculations showed that the RCS pressure cannot be reduced below about 120 psia (i.e., the pressure required for sufficient RHR low pressure injection flow to begin flushing the core) for at least 8.0 hrs when 2 ADVs and 2 PORVs are opened at one hour following a 0.0125 ft2 cold leg break. The staff calculations suggest that with the RCS boiling for extended periods of time, or more than

8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in this example, large amo the RCS pressure remains above keep the boric acid in solution. A regain power or the ability to mor inadvertently produced. It would the operators not to exceed the m Staff calculations also show that t one of the ADVs fail to open. Wh the RCS to 120 psia for small brea maintain the boric acid in solution stay within the limits of the permi causing an inadvertent precipitati breaks in the event boiling persis above 120 psia (or that RCS press boric acid).

Please provide information as to h operators to not exceed the perm These clarifications were discussed December 20, 2010. The informatio staffs review associated with the ex Sincerely, Terry A. Beltz, Senior Project Manager NRR/ADRO/DORL/LPL3-1 (301) 415-3049 ounts of boric acid can accumulate in the ves 120 psia, the RCS temperature is sufficiently As such, there is the concern that should oper re rapidly depressurize the RCS, precipitation therefore be important for the EOPs to instru maximum cooldown limit following a small bre the operators could also utilize the PORVs sh hile the staff finds that one ADV may not depre aks for many hours, the high RCS temperature

n. Potential modifications to the EOPs or guid ssible cooldown rates will prevent the operat ion by limiting the depressurization rate durin t for extended periods of time with the RCS p sure where LPSI injection can flush the core t how the EOPs and operating procedures instr issible cooldown limits following a SBLOCA.

with you and your staff during a teleconference o on being requested is necessary to complete the xtended power uprate license amendment reques ssel. While high to rators could be uct or alert eak LOCA.

hould only essurize e will dance to ors from ng small ressure to control ruct the on SNPB st.